Walking beam furnace control

ABSTRACT

A control system for a walking beam furnace including a charging mechanism, which system includes settable walking beam and charging control means, and comparator means for comparing the charge space available in the furnace with the size and spacing of the work pieces to be charged and for regulating the distance of movement of the charging mechanism in accordance with the available charge space.

I United States Patent 1 3,575,394

[72] inventors Regis A. Gaj; [56] References Cited Joseph J. Fabry, Scott Township, Allegheny TED STATES PATENTS [7H Appl NO gfgg g 3,450,394 6/1969 Wildeet al 263/6A 221 Filed July 10, 1969 FOREIGN PATENTS [45] Patented Apr. 20, 1971 846,466 8/1960 Great Britain 263/6A [73] Assignee Salen-Brosius, Inc. 1,503,970 10/1967 France 263/6 Primary Examiner-Charles J. Myhre Att0rney-Buell, Blenko and Ziesenheim ABSTRACT: A control system for a walking beam furnace [54] Ya F gg M E CONTROL including a charging mechanism, which system includes alms rawmg settable walking beam and charging control means, and [52] U.S. Cl 263/6, comparator means for comparing the charge space available l98/219 in the furnace with the size and spacing of the work pieces to [5 l 1 Int. Cl F27b 9/14 be charged and for regulating the distance of movement of the [50] Field of Search 263/6, 6 charging mechanism in accordance with the available charge (A); 198/219 space.

WALKING BEAM FURNACE CONTROL This invention relates to a control system for a walking beam furnace, and particularly to a control system for regulating the spacing of work pieces in the furnace. This invention provides an automated system for spacing work pieces, such as billets, castings or the like, in a walking beam type of a heating furnace.

Heretofore, work piece spacing was controlled in a manual fashion in that an operator would regulate the pusher and walking beam strokes to accord with the size and spacing of the work pieces to be charged into the furnace. When the size and spacing of the work pieces changed the operator would change the strokes of the pusher and walking beam accordingly. In order to properly regulate the pusher stroke during the changeover of work piece sizes, the operator would have to calculate or estimate his available charge space and then operate the stroke of the pusher accordingly. This method was subject to human error and could result in improper work piece spacing and thus improper heating of the work pieces.

The present invention eliminates human error in spacing work pieces in a walking beam heating furnace by providing an automatic system for ascertaining the available charge space in the furnace and comparing it with the size and spacing of the work pieces to be charged and controlling the stroke of the charging mechanism accordingly. More particularly, this invention, in preferred form, is directed to a control system for a walking beam furnace including a walking beam mechanism for moving work pieces a desired distance longitudinally of the furnace, and a charging mechanism for positioning work pieces a desired distance into the furnace, the control system comprising: walking beam control means for selectively controlling the longitudinal movement of the walking beam mechanism; charging control means for controlling the longitudinal movement of the charging mechanism to thereby charge a work piece into a desired position in said furnace; and comparator means operative between both of the aforesaid control means for comparing the charge space available in the furnace with the size and spacing of the work pieces to be charged, and for regulating the distance of longitudinal movement of the charging mechanism in accordance with the available charge space.

Other details and advantages of the invention will become apparent as the following description of a present preferred embodiment thereof proceeds.

In the accompanying drawings we have shown a present preferred embodiment of the invention in which:

PK]. 11 is a diagrammatic side elevational representation, partially cut away, of a walking beam type heating furnace, showing portions of the present invention;

FIG. 2 is a view looking along the line ll-ll of H6. 1;

FIG. 3 is a schematic representation of a control system showing certain parts of the present invention; and

H05. 4 and 5 are schematic representations of sequences of movement of work pieces through a heating furnace.

Referring now to the drawings, and particularly to FIGS. 1 and 2, reference 110 generally designates a diagrammatic representation of a walking beam type heating furnace of conventional construction, including an elongated housing 12 having a charge end 14 for receiving work pieces l5 and a discharge end 116 through which the work pieces are withdrawn. Disposed within the confines of housing 12 is a walking beam mechanism 20 including a lifting mechanism 22 operative with a traverse mechanism 24 including a movable beam 26 upon which work pieces R5 are supported when the walking beam mechanism 20 is activated to move the work pieces longitudinally of housing B2. Walking beam mechanism 20 can be of any conventional design so long as it is capable of traversing work pieces through the furnace. Work pieces are supported on stationary beams 26 in between traverses of the walking beam mechanism. Work pieces 115 are advanced into housing ll2 through the charge end 14 by a pusher 30 and removed through the discharge end l6 by an extractor 32.

both of which pusher and extractor can be of conventional design. The control system of this invention coordinates the movement of walking beam mechanism 20 with pusher 30 such that work pieces 15 are pushed into the furnace in accordance with the size and desired spacing of the work pieces. This will be better understood and appreciated when later on herein typical examples of movements of different size work pieces through the furnace are described.

Referring to FIGS. 1 and 3, the control system of this invention includes a suitably supported walking beam pulse generator 40 having a rotatable pinion 42 engaging a gear rack 44 suitablyfixed to traverse mechanism 24 of walking beam mechanism 20. Walking beam pulse generator 40 is of any conventional design, and is appropriately geared to generate pulse counts equivalent to the longitudinal movement of traverse mechanism 24. Walking beam pulse generator 40 is connected with a selectively settable walking beam stroke counter 46 of standard design controlling the longitudinal movement of the traverse mechanism 24. Traverse mechanism 24 is driven by an electric motor 48 which is connected to a control panel 50 through a beam traverse starter 52. Walking beam pulse generator 40 is also connected to a space setting comparator 60 of standard design. Walking beam pulse generator '40 feeds pulses to space setting comparator 60, which pulses will be equivalent to the charge space in the furnace. The charge space is the space available for receiving a work piece, and would be measured from a zero reference point (usually inwardly adjacent the charge end of the furnace) to the trailing edge of the last work piece charged. Pusher 30 also has associated with it a suitably supported pusher pulse generator 64 having a rotatable pinion 66 engaging a gear rack 68 suitably mounted on pusher 30. Pusher pulse generator 64 is of conventional design, and is appropriately geared to generate pulse counts equivalent to the longitudinal movement of pusher 30. The pulse count setting of pusher pulse generator 64 is preferably the same as that of walking beam pulse generator 40. Pusher pulse generator 64 is connected with a selectively settable pusher counter 70 of conventional design which serves to control the length of stroke of pusher 30 by feeding an appropriate signal through control panel 50 to which it is connected to an electric motor 72 also connected to the control panel through a pusher starter 74. Pusher counter 70 is also connected to space setting comparator 60 which will compare the pulse counts received from walking beam pulse generator 40 with those received from pusher pulse generator 64. Thus, the charge space available in the furnace will be compared with the pusher 30 count setting. Space setting comparator 60 and pusher counter 70 are connected in such a manner that the comparator will feed the charge space count to the pusher counter which in turn will control the length of stroke of pusher 30. Pusher counter 70 is set initially to control the length of desired stroke of pusher 30 which length would provide a desired spacing between the work pieces in the furnace. Pusher counter 70 is thus set to provide a desired trailing end to trailing end spacing between sequentially spaced work pieces. As will be described more fully hereinafter, the stroke of pusher 30 will change when one size batch of work pieces is to be charged into a furnace already containing work pieces of another size. In such a situation, walking beam stroke counter 46 would be set to control traverse mechanism 24 to move the work pieces already in the furnace, while pusher counter 70 would be set to control pusher 30 to push the new work pieces into the furnace. The following description of illustrated examples will make this more clearly understandable.

FIGS. 4 and 5 schematically illustrate typical examples of movements of batches of different sized work pieces through a furnace. In FIG. 4 the furnace would be filled with 12 inch X 20 inch billets with the next batch coming in being 10 inch X 14 inch billets 32. The desired spacing between 12X20 billets is, for example, 3.6 inches, which upon taking into account the 20-inch length of the billet would thus require a walking beam traverse 23.6 inches. Similarly, the desired spacing between l l4 billets is 3.0 inches thus requiring a pusher stroke that will give a center to center distance of 17.0 inches between billets. Accordingly. walking beam stroke counter 46 would be set to give a 23.6-inch traverse movement to traverse mechanism 24 and pusher counter 70 would be set to provide a stroke for 17.0-inch spacing. Setting the pulse generators so as to count one revolution of their pinions to 0.01 inches of travel of the respective pusher and traverse mechanisms, walking beam stroke counter 46 therefore would be set for 23.6 inches or 2,360 counts and pusher counter 70 for 17 inches or 1,700 counts. Just prior to charging the first 14 billet, traverse mechanism 24 will move the billets 23.6 inches, thus making a charge space available for the new work of 23.6 inches. Space setting comparator 60 is fed the 2,360 count and compares it with the 1,700 count received from pusher counter 70. The 1,700 count is subtracted from the 2,360 count leaving 660 counts, which is called the set point of the comparator 60. The set point is fed back to pusher counter 70 which then permits motor 72 to give an additional 6.6-inch stroke to the present stroke of pusher 30. Thus, as shown in sequence 2 of FIG. 4, a 3.0-inch space is achieved between the first l0 l4 billet and the last of the 12 20 billets. In addition, a 6.6-inch spacing exists between the charge end (zero reference) and the trailing edge of the first 10X 1 4 billet. Comparator 60 stores or retains the 660 counts. Traverse mechanism 24 will then move another 23.6 inches and a 2,360 count will be fed to comparator 60 which will add the 2,360 to the stored 660 giving 3,020 counts. The 3,020 counts are compared with the 1,700 counts set on pusher counter 70, giving a set point of 1,320 counts. The 1,320 counts are fed back to the pusher counter which then controls pusher 30 to stroke an additional 13.2 inches to its preset stroke. Another 23.6-inch traverse is made; 2,360 counts are added to the stored 1,320 set point count to get 3,280 counts from which is subtracted the 1,700 counts to give a set point remainder of 1,980 counts. whereupon, the pusher is advanced an additional 19.8 inches and another subtraction is made between the 1,980 count and 1,700 count to give a 280 count remainder, and accordingly pusher 30 makes another stroke 2.8 inches beyond its preset stroke. The set point on the comparator is now 280 counts. The same procedure is continued (i.e., 2.360 counts added to the set point, 1,700 counts being subtracted from the total, the pusher controlled to give additional stroke) until the furnace is filled with 10x14 billets, at which time walking beam stroke counter 46 is set to 1,700 counts. At this point the set point on the comparator will be zero, whereby the desired spacing will be 17.0 inches, the same as the traverse of traverse mechanism 24, and, of course, will remain zero so long as the size of the billets remains the same.

FIG. 5 schematically illustrates another example of different size batches going through the furnace. In this example we go from smaller to larger size, 8 inch X 8 inch billets 84 to 12 inch X inch billets 80. The selected spacing for the 8X8 billets is 2.4 inches, whereby the trailing end to trailing end dimension or stroke is 10.4 inches. Accordingly, walking beam stroke counter 46 is set for 1,040 counts. Pusher counter 70 is set for the 12 20 billets. The selected spacing between the 12X20 billets is 3.6 inches, whereby the trailing end to trailing end dimension is 23.6 inches. Accordingly. pusher counter 70 is set at 2,360 counts. After the first traverse of traverse mechanism 24, a count of 1,040 is fed into space setting comparator 60. The 1,040 is compared with the 2,360 fed in from pusher counter 70. Pusher counter 70 is preset so as to reject any negative numbers. and therefore motor 72 for pusher 30 cannot receive any signal to operate at this time. When traverse mechanism 24 steps another 10.4 inches, another 1,040 counts are fed into comparator 60. The second 1,040 counts are added with the first 1,040 counts to total 2,080 counts. The 2,080 counts then are compared with the 2,360 counts, and since a negative number results, again no signal can be sent to the motor 72 to activate pusher 30.

Traverse mechanism 24 will then step another 10.4 inches; an additional 1,040 counts will be fed to comparator 60 and added to the 2,080 set point to total 3,120 counts from which is subtracted the 2,360 count to get a 760 count remainder or set point. In this case, the pusher counter will be fed a positive 760 count signal and will accordingly activate motor 72 and permit an additional 7.6-inch stroke to pusher 30. The new set point on the comparator being 760 counts, a further traverse of traverse mechanism 24 will result in comparator 60 reaching a count of 1,800 counts which again would not be enough to cause pusher counter 70 to activate motor 72. The next traverse of traverse mechanism 24 would result in a reading of 2,840 counts on comparator 60 from which would be subtracted the 2,360 count pusher counter setting, giving 480 counts and permitting an additional 4.8-inch stroke to the stroke setting of pusher 30. The 6th sequence of FIG. 5 would result in a reading of 1,520 on the comparator 60 and accordingly no operation of pusher 30 occurs. The 7th sequence would result in a 2,560 count, which would permit activation of the pusher with a resultant 200 count set point whereby pusher 30 will be given an additional 2.0-inch stroke. The sequence continues as indicated until the furnace is filled with X20 billets and the set point is zero, at which time walking beam stroke counter 46 is set to 2,360 counts.

From the foregoing, it is readily apparent that this invention provides an automatic control system for any desired spacing and handling of batches of different size work pieces in a walking beam heating furnace.

Still another important advantage of the invention that will be readily apparent to those skilled in the art is that the system automatically compensates for any coasting" of the walking beam mechanism, sometimes referred to as "drift," after the stop" signal occurs. 1n the system of this invention the counter resets instantaneously at the time it gives the stop" signal and counts in accordance with the amount of travel or drift which occurs after this signal is given. The counter then begins counting from this new number when the next stroke is made and thus eliminates any accumulative error in successive walks and compensates for brake wear and the like to maintain a uniform stroke length. Various modifications can be made to the system described as will be readily apparent to those skilled in this art.

While 1 have shown and described a present preferred embodiment of the present invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied within the scope of the following claims.

lclaim:

1. A control system for a walking beam furnace comprising, in combination:

a walking beam mechanism for moving work pieces a desired distance longitudinally of the furnace;

a charging mechanism for positioning work pieces a desired distance into the furnace; walking beam control means for selectively controlling the longitudinal movement of said walking beam mechanism;

charging control means for controlling the longitudinal movement of said charging mechanism to thereby charge a work piece into a desired position in said furnace; and

comparator means operative between both of said control means for comparing the charge space available in the furnace with the size and spacing of the work pieces to be charged, and for regulating the distance of longitudinal movement of said charging mechanism in accordance with the available charge space.

2. A control system as set forth in claim I wherein said charging control means includes means limiting operation of said charging mechanism to operate only when the charge space available in the furnace is substantially equal to or greater than the size and spacing of the work to be charged.

3. A control system for a walking beam furnace comprising, in combination:

a walking beam mechanism for moving work pieces a desired distance longitudinally of the furnace;

a charging mechanism for pushing work pieces a desired distance into the furnace;

walking beam control means operative with said walking beam mechanism and selectively settable for controlling the distance of longitudinal movement of said walking beam mechanism;

charging control means operative with said charging mechanism and selectively settable for controlling the distance of longitudinal movement of said charging mechanism to thereby push a work piece into the furnace in the desired spaced relationship with the previous work piece;

comparator means operative with both of said control means for comparing available charge space with the size of the work to be charged plus the desired spacing between said work pieces, and for regulating said charging control means in accordance with the available charge space such that the charging mechanism advances a work piece any additional distance required to obtain said spacing; and

said charging control means including means operative to limit operation of the charging mechanism to charge work into the furnace only when the available charge space in the furnace is substantially equal to or greater than the size of the work to be charged plus the desired spacing between successive work pieces.

4. A control system as set forth in claim 3 wherein said walking beam control means includes pulse generating means for transmitting pulses equivalent to the longitudinal movement of said walking beam mechanism, which pulses are fed at least to said comparator means; said charging control means including pulse counter means for receiving pulses from said comparator means and a pulse generator for transmitting pulses to said pulse counter means, said pulse counter means transmitting pulses to said charging mechanism to thereby push work pieces into said furnace in accordance with the available charge space.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION pate 3 ,575 394 Dated April 20 1971 R is A. Ga' et a1. Inventor(s) J It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet [73] "Salen-Brosius Inc." should reac Salem Corporation, a corporation of Pennsylvania COlUJTII line 21 "present" should read pre-set line 36 "3, 280" should read 3 ,680 Column 4 line 23 after "with" insert 12 Signed and sealed this 7th day of September 1971 (SEAL) Attest:

EDWARD M. FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Pate 

1. A control system for a walking beam furnace comprising, in combination: a walking beam mechanism for moving work pieces a desired distance longitudinally of the furnace; a charging mechanism for positioning work pieces a desired distance into the furnace; walking beam control means for selectively controlling the longitudinal movement of said walking beam mechanism; charging control means for controlling the longitudinal movement of said charging mechanism to thereby charge a work piece into a desired position in said furnace; and comparator means operative between both of said control means for comparing the charge space available in the furnace with the size and spacing of the work pieces to be charged, and for regulating the distance of longitudinal movement of said charging mechanism in accordance with the available charge space.
 2. A control system as set forth in claim 1 wherein said charging control means includes means limiting operation of said charging mechanism to operate only when the charge space available in the furnace is substantially equal to or greater than the size and spacing of the work to be charged.
 3. A control system for a walking beam furnace comprising, in combination: a walking beam mechanism for moving work pieces a desired distance longitudinally of the furnace; a charging mechanism for pushing work pieces a desired distance into the furnace; walking beam control means operative with said walking beam mechanism and selectively settable for controlling the distance of longitudinal movement of said walking beam mechanism; charging control means operative with said charging mechanism and selectively settable for controlling the distance of longitudinal movement of said charging mechanism to thereby push a work piece into the furnace in the desired spaced relationship with the previous work piece; comparator means operative with both of said control means for comparing available charge space with the size of the work to be charged plus the desired spacing between said work pieces, and for regulating said charging control means in accordance with the available charge space such that the charging mechanism advances a work piece any additional distance required to obtain said spacing; and said charging control means including means operative to limit operation of the charging mechanism to charge work into the furnace only when the available charge space in the furnace is substantially equal to or greater than the size of the work to be charged plus the desired spacing between successive work pieces.
 4. A control system as set forth in claim 3 wherein said walking beam control means includes pulse generating means for transmitting pulses equivalent to the longitudinal movement of said walking beam mechanism, which pulses are fed at least to said comparator means; said charging control means including pulse counter means for receiving pulses from said comparator means and a pulse generator for transmitting pulses to said pulse counter means, said pulse counter means transmitting pulses to said charging mechanism to thereby push work pieces into said furnace in accordance with the available charge space. 